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GUNS Magazine October 2010 - Page 16
• JACOB GOTTFREDSON • USinG HoLDoVER BARS Quickly now. ometime back I asked friends how they would use holdover bars S to make an extremely quick determination of which holdover bar to use. It was a quiz of sorts. Since they didn’t respond with an used by the Military for generations in their mil dot scopes. Instead of each bar subtending 2" at 100 yards, they subtend 3.6". It makes the math a bit answer, I thought I’d better go ahead and provide it here. more cumbersome, and in some cases ranging is Over the past 15 years, the industry horizontal crosshair on the more difficult because of has gone from the simple plex reticle top of the target and then the distance between each to a reticle with bars on the vertical count down the number dot. The size of the dot crosshair below the main, horizontal of bars to the bottom of often covers the target crosshair. Some have them above and the target. You happen to entirely, which gave rise to some have them on the horizontal be using a 7mm SAUM Leupold’s TMR, Valdada’s MEnA SUVARi Barnes crosshair as well. The explosion on this with 140-grain MP-8, Schmidt & Bender, theme by manufacturers has begun to Triple Shock bullets and a and others with slim bars make my eyes go crossed. Dots, circles, Nightforce scope with their thisisthenewBRX instead of dots. But the bars, upside down Christmas trees, NP-R2 reticle. Assume each reticlefromSwarovski. basic idea is identical. asymptotic curves. The list goes on. bar in my example subtends Insteadofplacingthe Snipers often use another For anyone shooting at targets or 2" at 100 yards (see side barsatevenincrements technique. Once situated in animals, the bars are a tremendous bar). You note bar number ofsubtension,theyusea a stand or hide, they map help in determining range, holding 2 is exactly at the bottom methodofballisticcurves, the area in front of them off for wind, and knowing rather than of the target. In your head thus,thebarsubtension and then range several guessing holdover to make first round you figure 24" ÷ (2" per bar issomethinglike1.8", objects. When something hits. You simply determine ahead of x 2 bars) = 600 yards. Since 5.4",9",12.6"and16.2". appears, they already have time where each bar, or dot, etc. reflects each bar subtends 2" at 100 thatstillfitsthemethod the distance and either dial the point of impact of the bullet at yards, the second bar down ofsolutionpresentedhere, for it or use the bars or dots some range. from the main horizontal asdoesanystyleofbars, for holdover. For simplicity’s sake, let’s assume crosshair is 2" + 2" = 4", and circles,dots,orwhatever. But suppose the target you see an elk at rather long distance 24" divided by 4" = 6 x 100 Youonlyneedtoknowthe doesn’t wait around while and you decide to use the bars to range = 600 yards. you do all that. Suppose subtensionat100yards the animal. You decide the target’s You know from your ofeachlinecrossingthe the target is a royal chest area is 24" tall. You put the main ballistic software and from mainverticalcrosshair. majestic bull you paid shooting on the dearly to find and take. range if you put Suppose you suddenly bar number 6, for example, spot him on the way back to camp. it will be a holdover of 10" That is a lot of supposing, but not at 100 yards and will result uncommon. He is about to go into in a hit at 600 yards. You the trees, and you realize you’ll never fire and hit the elk in the kill see him or another like him as long zone. Down he goes and the as you live. There is no time for a winter is spent showing off rangefinder, no time for a solid rest. his horns and enjoying your You have to determine the range and favorite elk recipe. Life is the bar to use in the next four seconds good! and fire in the following two seconds. There are three basic As a second difficulty (quiz), let’s premises in all this. 1) You assume the animal is at an angle of had a very good rest that about 20 degrees up or down. We will allowed you to hold the rifle leave that one for a moment. steady while you ranged The solution to both problems and shot. 2) The animal was begins at home, first with some obliging enough to stand thinking, second with some playing theExbalprogramfromwww.Perry-Systems.comcalculates still while you accomplished with your favorite ballistics program, thezeroofeachbar(foranyconfigurationofbars).Italso number one. 3) There was and finally with some time on the tellsyouthelowhitandthehighhitforanykillzoneyou sufficient time. range. In a nutshell, here is how it pick.Inthisexample,Jacobpickedan8"killzone.the That is the concept works. Your bull elk is approximately softwarecalculatesthenumbersasshown.thetableisfora behind the development of 28" deep just behind the shoulder .308Winchester,175-grainbulletatstandardenvironmental holdover bars. It has been (don’t get too fixated on an elk. conditions. the basic methodology This will work for any animal). You 16 WWW.GUNSMAGAZINE.COM • OCTOBER 2010